1. Field of the Invention
The present invention relates generally to electro-optic systems, and in particular but not exclusively, relates to the mounting of electro-optic systems.
2. Background Information
An alternative to hardwired or fiber network communication solutions is the use of wireless optical communications. Wireless optical communications utilize point-to-point communications through free space and therefore do not require the routing of cables or fibers between locations. Thus, wireless optical communications are also known as free space or atmospheric optical communications. For instance, in a free space optical communication system, a beam of light is directed through free space from a transmitter at a first location to a receiver at a second location. Data or information is encoded into the beam of light, and therefore, the information is transmitted through free space from the first location to the second location.
An important aspect of a free space optical communications system is pointing and tracking. In particular, it is important that the optical communications beam (e.g., laser beam) is aimed properly from the transmitter at the first location and that the receiver at the second location is aligned properly to receive the optical communications beam. For example, assume that a transmitter is mounted on a first building and that a receiver is mounted on a different second building. Assume further that there is a line of sight between the transmitter and receiver. It is important for the transmitter on the first building to be configured to accurately direct or aim the optical communications beam at the receiver on the second building.
Tracking is utilized for maintaining the alignment of the optical communications beam between the transmitter and receiver in various situations or disturbances. Examples of these various situations or disturbances include, building twist and tilt due to thermal expansion from non-uniform solar loading, the swaying of the buildings due to for example windy conditions, vibration of the platforms on which the transmitter and/or receiver are mounted, atmosphere-induced beam steering, etc. If the tracking system is unable to compensate for disturbances, the optical communications beam is no longer properly aimed at the receiver and, consequently, communications between the transmitter and receiver are lost or impaired.
These types of motions that affect the alignment of the communications beam are typically small in magnitude and occur at slow rates. Some types of telecommunications systems use yoke structures to perform positioning adjustments. However, these yoke structures often are not capable of very small and precise movements over a limited field-of-regard. Additionally, yoke structures and other mechanisms that perform positional adjustments using motorized tracking mounts often have multiple parts that require complex controls, are expensive to manufacture, are bulky and cumbersome to use, or may not provide sufficient positional stiffness needed for optical telecommunications systems.
One aspect of the invention provides an apparatus having an outer element. An inner element is positioned interior to the outer element and is coupled to the outer element by a first pivot element. A second pivot element is coupled interior to the inner element and is coupleable to an electro-optical telecommunication device. The first pivot element is positioned to allow movement of the inner element about a first axis, and the second pivot element is positioned to allow movement of the electro-optical telecommunication device about a second axis.